On Friday Damon confirmed those reports, but said he was yet to see a screenplay.

"I haven't seen a script yet but I have been talking to [director] Gary Ross about that for over a year and we are both really excited to do it," he said in an interview promoting his upcoming action film, Green Zone.

"You have always got to wait for the script. Gary is a great writer and a great director, so I am confident that it is going to happen. The script is coming in next month."

Ross wrote and directed 2003 Oscar-nominated movie Seabiscuit, and he is attached to direct the Kennedy film, which does not yet have a title.

The movie will be based on Evan Thomas' biography, His Life, and the script written by Steven Knight, according to media reports.